Prediction of maximal heart rate in individuals with mental retardation.

PURPOSE: It is well known that individuals with mental retardation (MR), especially those with Down syndrome (DS), have low maximal heart rates (MHR). We evaluated the ability to predict MHR in individuals with MR and DS in comparison with persons without MR. METHODS: Subjects completed a maximal exercise test on the treadmill with metabolic and HR measurements. Stepwise multiple regression was used to develop prediction equations for subjects with MR (N = 276; 97 with DS) and without (N = 296) MR, ranging in age from 9-46 yr. RESULTS: Subjects with MR exhibited significantly lower MHR (177 vs 185 beats.min(-1)) and VO2peak (33.8 vs 35.6 mL.kg-1.min(-1)). In subjects with MR, age was a poor predictor of MHR, Y = 189 - 0.59 (age) (R = 0.30, SEE = 13.8 beats.min-1; P < 0.01), but age was a better predictor for subjects without MR, Y = 205 - 0.64 (age) (R = 0.52, SEE = 9.9 beats.min(-1); P < 0.01). A large sample Z test indicated that these regression coefficients were significantly different (P < 0.01). However, adding DS to the regression improved the prediction for subjects with MR, Y = 210 - (0.56 age) - (15.5 DS) (R = 0.57; SEE = 11.8 beats.min(-1), P < 0.01). CONCLUSION: MHR can be predicted with similar accuracy in subjects with and without MR, provided DS is accounted for in the equation for the subjects with MR.

Effects of an aerobic rowing training regimen in young adults with Down syndrome.

Effects of a rowing exercise regimen on cardiovascular fitness of young adults with Down syndrome were examined. Sixteen young males with trisomy 21 (mean age 21.3, mean IQ 38.8) were randomly assigned to either a control or exercise group. All participants performed pre- and posttraining graded exercise tests on a treadmill and rowing ergometer. The exercise group performed a 16-week rowing ergometry training regimen. Following training, no changes in cardiovascular fitness had occurred for this group. However, they reached significantly higher levels of work performance for both treadmill and rowing ergometer posttraining tests. Results show that an exercise training regimen did not improve the cardiovascular fitness of young adults with Down syndrome but did improve exercise endurance and work capacity.

Physical activity for the chronically ill and disabled.

Exercise prescription principles for persons without chronic disease and/or disability are based on well developed scientific information. While there are varied objectives for being physically active, including enhancing physical fitness, promoting health by reducing the risk for chronic disease and ensuring safety during exercise participation, the essence of the exercise prescription is based on individual interests, health needs and clinical status, and therefore the aforementioned goals do not always carry equal weight. In the same manner, the principles of exercise prescription for persons with chronic disease and/or disability should place more emphasis on the patient's clinical status and, as a result, the exercise mode, intensity, frequency and duration are usually modified according to their clinical condition. Presently, these exercise prescription principles have been scientifically defined for clients with coronary heart disease. However, other diseases and/or disabilities have been studied less (e.g. renal failure, cancer, chronic fatigue syndrome, cerebral palsy). This article reviews these issues with specific reference to persons with chronic diseases and disabilities.

Comparison of isokinetic peak force and work parameters in youth with and without mental retardation.

PURPOSE: The purpose of this study was to compare isokinetic knee (flexion and extension) strength of nondisabled youth (ND; 15 males, 15 females; males = 12.7 +/- 2 yr; females = 13.4 +/- 2 yr) and youths with mental retardations (MR, 17 males + 13 females; male = 14.7 +/- 2 yr; females = 13.6 +/- 2 yr). METHODS: Subjects were evaluated on a Kin-Con isokinetic dynamometer at a speed of 60 degrees x s(-1). Parameters measured were peak torque (PT), time to PT, angle of PT, total work (W), and PT hamstrings/quadriceps (HQ) ratio. Peak torque was also corrected by weight (BW) and body mass index (BMI). Peak torque, time to peak torque, angle of peak torque, and total work were analyzed using a 2 x 2 x 2 (groups x gender x muscle) repeated measures analysis of variance (MANOVA). Flexion/extension ratios, BMI, and BW were analyzed by separate 2 x 2 (group x gender) analyses of variance. RESULTS: Results of this study suggest that: 1) while gender differences are apparent in the ND population they are not evident in individuals with MR; 2) knee extension strength is higher for ND youth, thus causing lower PT HQ ratios when compared with those in youth with MR; 3) angle of PT and time to PT were similar among groups; and 4) total work performed is lower in individuals with MR. CONCLUSIONS: It was concluded that parameters of strength production in individuals with MR are not consistent and do not follow the same pattern as their nonretarded peers.

Validation of cardiovascular fitness field tests in children with mental retardation.

The validity of the 600-yard walk/run, the 20-m shuttle run, and a modified 16-m shuttle run was determined to measure aerobic capacity (VO2peak) in children with mild and moderate mental retardation. Practice sessions for all tests were conducted. All field tests were very reliable, and VO2peak was significantly related to them all. A stepwise multiple regression showed that field test performance, body mass index (BMI), and gender, but not age, were also significant predictors of VO2peak. All field tests were valid and reliable indicators of aerobic capacity, suggesting that these tests can be used to predict VO2max in children with mild and moderate mental retardation.

Isokinetic torque, average power, and flexion/extension ratios in nondisabled adults and adults with mental retardation.

For successful placement of individuals with mental retardation into community environments, a minimal amount of functional strength is required to promote self-independence. Since muscular strength and power are commonly deficient in these groups, the purpose of this study was to compare isokinetic elbow flexion and extension peak torque (Nm), average power (W), and corresponding flexion/extension ratios of adults males with Down syndrome, with mental retardation without Down syndrome, and sedentary adult males without mental retardation. Subjects with Down syndrome (N = 9), mental retardation without Down syndrome (N = 13), and without mental retardation (N = 13) were tested for elbow flexion and extension peak torque and average power at 60 and 90 degrees/sec on a Cybex 340 isokinetic dynamometer. Results indicated: 1) subjects without mental retardation displayed significantly greater ( p < 0.01) peak torque and average power elbow flexion and extension than subjects with Down syndrome and subjects with mental retardation without Down syndrome at speeds of 60 and 90 degrees/sec, and 2) there were no significant differences between groups in peak torque and average power elbow flexion/extension ratios at both angular velocities. The results of the data analysis support the premise that adults with mental retardation are in need of exercise programs to improve muscular strength.

Research on physical activity and disability: an emerging national priority.

Despite the voluminous amount of research that has been published in the field of exercise science over the past three decades, there remains a paucity of information on the activity patterns and physiological responses to exercise in persons with disabilities. In an era when physical activity has grown to new heights in terms of its importance in promoting health and preventing disease, many questions pertaining to how it affects the lives of individuals with physical disabilities remain unanswered. The purpose of this paper is to review the prevalence of disability in the United States and to present recommendations for future research on physical activity and disability. A related objective of this paper is to encourage exercise scientists to undertake research on this increasingly significant group of American citizens.

Peak torque, average power, and hamstrings/quadriceps ratios in nondisabled adults and adults with mental retardation.

OBJECTIVE: To compare isokinetic hamstring and quadriceps peak torque (Nm), average power (watts), and corresponding hamstring/quadriceps (HQ) ratios (as percentages) of adult men with Down syndrome(DS), with mental retardation without Down syndrome (NDS), and nondisabled sedentary controls (SC). DESIGN: Repeated measures analysis of variance. SETTING: Subjects were tested at a university exercise science laboratory. SUBJECTS: Volunteer sample of 35 subjects: SC(n=13), DS(n=9), and NDS (n=13). INTERVENTION: Subjects performed isokinetic strength tests at 60 degrees /sec and 90 degrees/sec using gravity effected torque procedures. Subjects with DS and NDS performed the test on two separate days with best results selected for statistical comparisons. Sedentary controls performed the test once. MAIN OUTCOME MEASURES: Isokinetic hamstring and quadriceps peak torque and average power, and corresponding HQ ratios on a Cybex 340 isokinetic dynamometer. RESULTS: In all isokinetic parameters measured, sedentary controls demonstrated significantly higher scores than subjects with DS and NDS. There was no significant difference between subjects with DS and NDS, although mean peak torque and average power scores were greater in subjects with NDS. Finally, there were no significant differences in peak torque and average power HQ ratios across groups (p> .01), although group mean peak torque HQ ratios were greatest for sedentary controls (range=61% to 63%) and approximated accepted HQ ratio norms, and lowest for subjects with DS(range=40% to 46%). CONCLUSIONS: Individuals with mental retardation are in need of progressive resistance exercise programs to improve hamstring and quadriceps strength and normalize HQ strength and power ratios.

Cardiorespiratory capacity of individuals with mental retardation including Down syndrome.

This study evaluated the cardiorespiratory capacity of persons with MR with and without Down syndrome. Analyses of individual data records of maximal exercise tests with metabolic analyses were conducted on tests of 111 subjects (31 men and 16 women with DS; 35 men and 29 women without DS) from six participating centers. All centers used a walking treadmill protocol previously shown to produce valid and reliable maximal tests with this population. Peak oxygen uptake and peak minute ventilation were higher in men than in women (P < 0.006), and in subjects without DS (P < 0.006). Peak heart rate was also higher in subjects without DS (P < 0.006). Peak respiratory exchange ratio (RER) was higher in subjects without DS (P < 0.006). Using peak RER as a covariate did not change the results. An analysis of peak minute ventilation, heart rate and VO2 of subjects with a peak RER above 1.1 revealed the same results. These data show that individuals with mental retardation have low levels of peak VO2, consistent with low levels of cardiovascular fitness. Individuals with Down syndrome have even lower levels of peak VO2 than their peers without Down syndrome, a finding that is possibly mitigated by the lower peak heart rates of the individuals with Down syndrome.

Cardiovascular fitness as related to leg strength in adults with mental retardation.

The purpose of this study was to compare cardiovascular fitness to leg strength of young adults (mean age = 25.2 yr) with mental retardation (MR) with and without Down syndrome (DS) and to determine whether a relationship exists. Thirteen adults (9 males, 4 females) with DS and 24 adults (16 males, 8 females) with MR but without DS participated in this study. Cardiovascular capacity (VO2peak) for each subject was determined by a treadmill test (GXT) and isokinetic knee flexion and extension strength (peak torque and average power) were determined by isokinetic dynamometry. Results generally demonstrated significant positive relationships (P < 0.05) between VO2peak and isokinetic leg strength (r = 0.61), with the relationship being substantial mainly for subjects with Down syndrome (r = 0.84). The results of this study suggest that leg strength may be an important contributor to VO2peak for persons with mental retardation.

An exploratory study of righting reactions from a supine to a standing position in adults with Down syndrome.

BACKGROUND AND PURPOSE: Standing from a supine position is important for physical independence. The purpose of this study was to determine the developmental level of movement in this righting task of adults with Down syndrome. SUBJECTS: Fifteen subjects (mean age = 37.6 years, SD = 18, range = 22-65) with a diagnosis of Down syndrome and mild to moderate mental retardation participated in this study. METHODS: Subjects were videotaped rising from a supine to a standing position during 10 repeated trials. The video record was analyzed to categorize the standing movements according to VanSant's descriptions. RESULTS: Sixty-four percent of the upper-extremity movements, 14.6% of the axial component movements, and 33.8% of the lower-extremity movements could not be categorized according to VanSant's descriptions. Additionally, developmentally less advanced movements dominated those movements that could be categorized. CONCLUSION AND DISCUSSION: The great variety of movements demonstrated by these subjects in the task of standing from a supine position suggests greater motor maturity than is apparent from the movement sequences described by VanSant. Identifying appropriate standing movements in persons with Down syndrome will require weighing numerous intrinsic factors (eg, physiological and anthropometric) other than motor maturity.

The effect of lower body positive pressure on the exercise capacity of individuals with spinal cord injury.

The purpose of this study was to determine the effect lower body positive pressure (LBPP) has on the cardiovascular/exercise capacities of individuals with spinal cord injury (SCI) during both arm crank exercise (ACE) and wheelchair exercise performed on a treadmill (WCTM). Ten male adults (age = 31.1 +/- 10 yr) with SCI and five male nondisabled (ND) adults (31.2 +/- 10 yr) participated in this study. The ND subjects performed ACE only. For subjects with SCI, significantly higher (P < 0.025) peak VO2 (1042 +/- 212 vs 839 +/- 218 ml.min-1), peak VE (46 +/- 17 vs 35 +/- 9 l.min-1), and work rate (50 +/- 15 vs 40 +/- 13 W) were seen during ACE with LBPP. No significant differences for peak VO2, VE, or work rate were seen for the ND subjects with LBPP during ACE. In addition, significantly higher peak VO2 (960 +/- 322 vs 828 +/- 312 ml.min-1) was recorded with LBPP for the subjects with SCI during WCTM. Cardiac output (Q, l.min-1; CO2 rebreathing method) was measured at 50% peak VO2 for both ND subjects and subjects with SCI during ACE. Subjects with SCI demonstrated significantly higher SV (94 +/- 20 vs 84 +/- 20 ml) with LBPP. No differences were observed in SV at 50% peak VO2 during ACE for the ND subjects with LBPP. The results of this study suggest that for individuals with SCI, LBPP augments exercise capacity by preventing the redistribution of blood to the lower extremities.

The accuracy of predicting treadmill VO2max for adults with mental retardation, with and without Down's syndrome, using ACSM gender- and activity-specific regression equations.

The purpose of this study was to examine the validity of the American College of Sports Medicine's (ACSM) prediction equations for calculating peak oxygen consumption (VO2max) in young adults with mental retardation. A total of 32 subjects with mental retardation participated in this study: 15 young adults with Down's syndrome (DS) and 17 non-DS young adults (NDS). Subjects were matched for age, gender and intelligence quotient (IQ). Subjects were given a standard treadmill-graded exercise test to determine peak heart rate (HR) and peak oxygen consumption (VO2max). Subjects were connected to a metabolic cart during the test. Peak VO2 was predicted using ACSM's prediction equations where predicted VO2max is: men, 57.8-0.445 (age); and women, 42.3-0.356 (age). Statistical significance between groups was determined using a two-tail t-test, with alpha set a priori at 0.05. The DS group had a significantly (P = 0.0003) lower peak HR (DS 155.90 +/- 12.12 vs NDS 175.38 +/- 9.87) and per cent HR achieved (P = 0.0007) (DS 80.26 +/- 6.76 vs NDS 89.39 +/- 4.46) as compared to the NDS group. Differences were also found between groups with respect to peak oxygen consumption. The DS had a significantly (P = 0.006) lower peak oxygen uptake (ml kg-1 min-1) as compared to the NDS group (23.68 +/- 4.01 vs 31.00 +/- 7.11, respectively). Significant differences (P = 0.007) were accordingly observed with respect to per cent predicted oxygen uptake achieved (DS 55.22 +/- 10.61 vs NDS 73.27 +/- 19.15). A nearly two-fold difference (P = 0.01) was observed with respect to the functional aerobic impairment between the DS (44.79 +/- 10.61) and NDS (28.29 +/- 18.63) groups, further illustrating the impaired peak cardiovascular capacities of both groups. The results of this study indicated that use of the ACSM gender and activity specific prediction equations in young adults with mental retardation (DS and NDS), peak VO2 is significantly over-predicted (83.9 and 39.2%, respectively). Therefore, peak oxygen consumption and derived exercise prescriptions must be based on actual measurements, rather than via ACSM prediction equations. Otherwise, training intensities may be over-predicted and impose possible health risks.

Endurance exercise training in Guillain-Barre syndrome.

The purpose of this case study was to determine whether an individual who had residual deficits following an acute incidence of Guillain-Barre Syndrome (GBS) would experience improved physiological adaptations following aerobic endurance training. A 57-year-old man who needed the aid of a crutch for walking three years following an acute bout of GBS participated in this study. Peak work level (watts), oxygen consumption (VO2 mL/min; mL/kg.min), and ventilation (VE, L/min) were determined on a bicycle ergometer (BE), a Schwinn Air-Dyne ergometer (SAE), and an arm crank ergometer (ACE) before and after exercise training. Isokinetic leg strength measured using a dynamometer and total work capacity in watts using BE were also determined before and after training. The subject trained for 16 weeks at an approximate frequency of 3 days/week, an average duration of 30 minutes, and an average intensity of 75% to 80% of pretraining peak HR. A 9% and 11% improvement was seen in peak oxygen consumption for the SAE and BE, respectively. For peak ventilation, a 23% and 11% improvement was seen for the SAE and BE, respectively. For the ACE, a 16% increase in peak ventilation was seen, with no improvement in aerobic capacity. Total work capacity on the BE was improved by 29% following training. Positive improvements were also seen in isokinetic leg strength. This study demonstrated that a man still suffering residual symptoms following an incidence of GBS was able to improve his cardiopulmonary and work capacity and isokinetic strength of his legs following a supervised training program using the SAE. The subject also reported improvements in activities of daily living.

Physical fitness and adults with mental retardation. An overview of current research and future directions.

The deinstitutionalization movement of the past 25 years has focused on the placement of people with mental retardation into community-based settings. There is a need for exercise- and health-related professionals to demonstrate a thorough understanding of the term mental retardation and all of the intellectual and behavioural ramifications that coexist with this condition before addressing the 'how to' of fitness evaluation. Therefore, the article outlines the range of intellectual and behavioural characteristics of this population, based on the level of retardation. Many researchers investigating body composition have reported that a disproportionate number of adults with mental retardation carry a percentage of body fat that would be considered unhealthy (e.g. it increases the risk of early onset of such diseases as hypertension and adult onset diabetes mellitus). Living arrangements (i.e. institution vs smaller residences) play a role in the prevalence of obesity. Many attempts of researchers to control weight in adults with mental retardation through caloric restriction, exercise, and a combination of diet and exercise, have had a varied outcome. Cardiovascular capacity is considered by most exercise physiologists as the major physiological indicator for overall fitness. The majority of researchers who have evaluated the cardiovascular fitness levels of adults with mental retardation have reported fitness levels representative of a very sedentary population. Therefore, one would expect a keen sense of urgency among researchers to develop training regimens targeted specifically for people with mental retardation. Many have been developed, but to date only 2 cardiovascular training regimens have been reported that specifically describe the necessary components of an exercise programme (i.e. frequency, duration, intensity) that would allow for reproducibility--a stationary bicycle routine using the Schwinn 'Air-Dyne' ergometer and a run/walk programme. Of these, only the programme using the Schwinn 'Air-Dyne' ergometer reported significant improvements in cardiopulmonary fitness. Researchers have demonstrated that: (1) body strength is valuable for recreation activities and activities of daily living; (2) competence in upper body muscular skills is a prerequisite for many available vocational opportunities; and (3) positive correlations have been established between muscular strength and industrial work performance in people with mental retardation. Therefore, there is a need for appropriate evaluation procedures for determining the muscular strength and endurance of people with mental retardation. The future directions for researchers and professionals concerned with the fitness status of people with mental retardation includes answering question such as: What will be the effect of obesity on general health status?(ABSTRACT TRUNCATED AT 400 WORDS)

Training of ambulatory individuals with cerebral palsy.

The effect of training on the physical work capacity (PWC) and the physiological response to simulated tasks of seven ambulatory individuals with cerebral palsy (CP) were studied. Energy demand for each work task was determined by percentage of PWC (%PWC). Results indicate that an eight week training program increased the PWC as evaluated by an exercise test on the Schwinn Air-Dyne Ergometer. The performance of the individuals for the simulated tasks measured in %PWC increased significantly, suggesting that individuals with CP could benefit from a training program and would be able to work eight hours before experiencing fatigue.

Introduction: exercise capacities and adaptations of people with chronic disabilities--current research, future directions, and widespread applicability.

This symposium addresses the unique physiological problems, current research, future needs, and widespread applicability for research involving people experiencing five major chronic disabilities within the United States: quadriplegia, paraplegia, mental retardation, multiple sclerosis, and poliomyelitis. Each author represents ACSM members who, by their distinguished research efforts, exemplify scientists who have demonstrated their dedication to the specific needs of these populations. The papers will give a brief description of the pathophysiology of the disability and the resultant effects upon the group's acute response to exercise and their physiological adaptations to exercise programs. Each paper will include reports on the state of current research and what benefits to that group could be expected if a major research breakthrough occurred. Additionally, the papers will indicate the major research questions currently confronting each population and a brief statement about the strategy needed to resolve these questions. If applicable, the authors will address how such a model (of the specific disability/disease) could be used to better understand the able-bodied response to exercise. The purpose of this symposium, therefore, was not only to better understand the effects of exercise on persons having chronic disabilities, but from a physiological point of view, to use what we know about the response of people with chronic disabilities to better understand the able-bodied response.

Isokinetic arm and leg strength of adults with Down syndrome: a comparative study.

This study compared isokinetic arm (elbow flexion and extension) and leg (knee flexion and extension) strength of individuals with Down syndrome (DS), with mental retardation without DS (NDS), and sedentary young adults with no mental retardation (NMR). Eighteen individuals with DS, NDS, and NMR (11 men and seven women in each group) performed strength tests on a Cybex 340 isokinetic dynamometer. Parameters measured were peak torque (ft/lb), peak torque percent body weight (%BW), average power (watts), and average power %BW. Subjects with mental retardation (ie, DS and NDS groups) performed the test on two separate days with best test results chosen for statistical comparisons. The NMR group performed the test once. In all isokinetic strength parameters measured for arm strength, the NMR group demonstrated significantly higher scores than subjects with DS and NDS. Subjects with DS and NDS displayed similar test results. Similarly, for all the isokinetic strength parameters measured for leg strength, NMR demonstrated significantly higher scores than subjects with DS and NDS. Subjects with NDS, however, averaged significantly higher test results than subjects with DS for leg strength. The results of this study indicate that both subject populations who were mentally retarded exhibited lower arm and leg strength than the NMR subjects. Additionally, subjects with DS demonstrated inferior leg strength when compared to their peers with NDS.

The cardiovascular capacities of adults with Down syndrome: a comparative study.

The purpose of this study was to compare the cardiovascular capacities of individuals with Down syndrome (DS) to individuals without Down syndrome who are mentally retarded. Sixteen young adults with DS and 16 individuals without DS (12 males and 4 females, respectively), all with mild/moderate mental retardation, participated in this study. Peak VO2 (absolute and relative), VE (1.min-1), heart rate (HR, b.min-1), and RER (VCO2/VO2) were determined by exercise tests utilizing a treadmill (TM) and Schwinn Air-Dyne ergometer (SAE). The best test result was chosen from the TM and SAE tests and used for statistical comparisons. Cardiac output (Q, 1.min-1) was measured while standing quietly and while walking at 3 mph, 0% grade, using the CO2 rebreathing method for 11 (9 males and 2 females) subjects from each group. Arteriovenous oxygen differences (a-v O2), cardiac index (QI), and stroke volume (SV) were calculated from VO2, Q, HR, and body surface area. Peripheral vascular resistance (PVR), left ventricular work index (LVWI), and left ventricular stroke work index (LVSWI) were calculated from mean arterial pressure, Q, QI, and stroke volume index. Results showed that individuals without DS had statistically significant (P less than 0.01) higher mean peak VO2 (35.6 vs 24.6 ml.kg-1.min-1; 2567 vs 1683 ml.min-1), VE (89.3 vs 59.2 1/min-1), and HR (179 vs 159 b.min-1) than individuals with DS, respectively. No differences in RER were seen between the groups. No differences were seen in cardiovascular parameters measured while quietly standing.(ABSTRACT TRUNCATED AT 250 WORDS)